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Endoscopic skull base surgeries

Endoscopic skull base surgeries

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Endoscopic skull base surgeries

  1. 1. Endoscopic skull base surgeries Dr Ajay kumar PDT NEUROSURGERY BIN KOLKATA
  2. 2. • Skull base surgery has been transformed by the development of endoscopic endonasal surgery. These techniques were initially developed for paranasal sinus surgery, but their indications have been gradually extended to include endoscopic resection of pituitary tumours, and then lesions of the clivus, olfactory cleft, planum sphenoidale, the petrous apex, or infratemporal fossa. • The major advantage of the endoscopic endonasal approach is that it provides direct anatomical access to a large number of intracranial and paranasal sinus lesions, avoiding the sequelae of a skin incision, facial bone flap or craniotomy, and brain retraction,
  3. 3. • Continued advances in surgical technique, navigation systems, endoscopic imaging technology, and robotics assure continued brisk evolution in this expanding field
  4. 4. • The history of endoscopic skull base surgery is de facto the history of pituitary surgery. The first pituitary operation was likely performed by Sir Victor Horsley in 1889 via a transfrontal approach though he did not publish his results • Schloffer who is widely regarded as the father of modern pituitary surgery. In 1906 he published a seminal paper discussing the possibility of pituitary surgery via a transsphenoidal approach and performed this operation on March 16, 1907.
  5. 5. • Then in 1910, Oskar Hirsh otolaryngologist, introduced a transseptal, transsphenoidal approach to the pituitary gland , an operation which is still in use today. • Cushing performed his first pituitary operation in 1909 using Schloffer's method but then rapidly adopted Hirsh's approach adding a sublabial incision and a headlamp to improve visualization of the sella.
  6. 6. • Hardy's contributions led to a paradigm shift in pituitary tumor surgery. Previously, the operation was performed to debulk large tumors off the optic apparatus, but now microsurgical techniques were introduced allowing for surgical cure of hormonal disease in microadenomas.
  7. 7. contributions • The first endoscope is credited to Philipp Bozzini, a German physician, who demonstrated the "Lichtleiter", a candlelit tube, in 1806 to the Academy of Medicine in Vienna • This was vastly improved in 1877 by Max Nitze, a German urologist, with the addition of lenses for magnification and an internal light source noting "to light up a room one must carry the lamp inside ." His first endoscope used a water- cooled platinum wire for illumination. • Edison's invention of the incandescent bulb in 1879 allowed the development of a cystoscope that no longer required water cooling. Using his invention, Nitze was the first person to perform endoscopic surgery with wire loops and to take endoscopic pictures.
  8. 8. • The next technological breakthrough occurred almost a century later when Harold Hopkins in 1960 vastly improved optical efficiency by inserting glass rods and neutral gas between the lenses. • Basil Hirschowitz, an American gastroenterologist, developed a flexible endoscope using fiberoptics.
  9. 9. • The modern rigid endoscope was invented by Karl Storz in 1965 when he combined the optical rod system of Hopkins and used fiberoptics to carry illumination down to the tip of the endoscope. This endoscope allowed radically improved visualization offering magnified panoramic views from the tip of a narrow caliber instrument. • Other important developments included the invention of computed tomography, image guidance systems and the charged coupled device camera.
  10. 10. • Endoscopic endonasal surgery provides access to almost all regions of the skull base situated anterior to the foramen magnum . Tumours are the lesions primarily concerned, but cerebrospinal fluid (CSF) leaks of traumatic or other origin, certain chronic infections and congenital malformations are also accessible to endoscopic surgery.
  11. 11. • Regions of the skull base situated in the midline and accessible to endoscopic surgery • olfactory cleft • planum sphenoidale, • sellar region, • clivus, • cervico-occipital junction.
  12. 12. • 1: transfrontal; • 2:transcribriform; • 3: transplanum; • 4: transsellar; • 5: transclival; • 6:transodontoid
  13. 13. LEVELS OF SKULL BASE SURGERY • Level 1 • Sinonasal surgery • Level 2 • Pituitary surgery • • CSF leaks • Level 3 • Extradural • Transcribriform • • Transplanum • • Transorbital (extraconal) • • Transclival • • Transodontoid • Level 4 • Intradural A. With cortical cuff • Transplanum • • Transcribriform • • Type I craniopharyngiomas • B. Lack of cortical cuff • Transorbital (intraconal) • • Transplanum • • Transcribriform • • Type II/III craniopharyngiomas • • Transclival intradural • Level 5 • Cerebrovascular surgery A. Middle and posterior coronal • planes • B. AVM/Aneurysms
  14. 14. • Illustration showing the skull base in an inferior view. • module of expanded endonasal approach at the skull base. CP-AF = coronal plane anterior fossa; • CP-MF = coronal • plane middle fossa; • CP-PF = coronal plane posterior fossa; • TC = transclival (pink area); TC = transcribriform (white area); • TO = transodontoid; • TP/T = transplanum/transtuberculum; • TS = transsellar.
  15. 15. • The growing interest of neurosurgeons in this “minimally invasive” surgery is due to the major progress made over recent years: a large number of anatomical studies, variants and innovations in exposure techniques and especially reconstruction have been reported. Constant progress in imaging, navigation systems, and instrumentation has also largely contributed to the growth of this surgery.
  16. 16. • A major criticism of endoscopic techniques is that they do not allow en bloc resection of the tumour. • complete resection of the zone of insertion: tumours often present an exophytic growth into paranasal sinuses from a smaller pedicle
  17. 17. • endonasal approach often allows resection without damaging adjacent healthy tissues, which is not the case with conventional open surgery, in which the skin, bone, and sometimes dura mater are opened to provide access to the tumour, with a risk of tumour seeding.
  18. 18. Instrumentation • videoendoscopy equipment and standard endonasal instrument • endoscopic endonasal skull base surgery may require the use of dedicated instruments • The microdebrider facilitates exposure time, particularly ethmoidectomy, and can also be used for resection in some cases, or at least for tumour dissection . • Some authors propose the use of ultrasonic surgical aspirators (Dissectron®, Cavitron®) for tumour dissection, and ultrasonic bone curettes have also been recently developed . • motors equipped with long handpieces allow drilling of the thickest portions of the skull base. • Angled burrs are particularly useful in the frontal sinus region .
  19. 19. • haemostasis systems mainly comprise sheathed monopolar cautery and bipolar forceps. Diode laser is also useful, particularly during mucosal dissection • navigation systems are widely available and are very useful for intraoperative anatomical localization; • some authors propose the use of a Doppler probe to localize large vessels
  20. 20. • An endoscope without irrigation system has a much smaller diameter and is therefore easier to use and is less traumatic to the nasal cavity. • A simple stream of saline from a syringe delivered by the assistant onto the shaft of the optic endoscope allows rinsing of the endoscope when it is soiled. • long, small-calibre dedicated instrumentation facilitates soft tissue dissection and intradural surgery
  21. 21. CRIBRIFORM LESIONS • olfactory groove meningioma • esthesioneuroblastoma, • adenocarcinoma, • squamous cell carcinoma, • sinonasal undifferentiated carcinoma • mucosal melanoma and others.
  22. 22. TRANSCRIBRIFORM APPROACH • Defined by the removal of the cribriform plate to approach skull base. • This approach extends anteriorly from the posterior ethmoidal arteries upto the level of the crista galli and frontal sinus. • The limits are  both laminae papyraceae laterally,  the frontal sinus anteriorly  the transition with the planum sphenoidale posteriorly at the level of the posterior ethmoidal arteries
  23. 23. CONTRAINDICATIONS  There are potential surgical limits laterally, posteriorly, and superiorly. LATERALLY- the midorbital plane -Removal of the lamina papyracea enables the displacement of the orbital soft tissues to provide access to the orbital roof laterally. Lesions that present a lateral extension beyond the midorbit meridian should not be accessed with a pure endonasal approach. POSTERIORLY—the optic chiasm and anterior cerebral circulation. Tumors lateral to the optic nerves should not be resected from a midline endonasal approach. Very tall tumors-difficult to access and care must be taken not to remove too much of the inferior and anterior capsule before the apex of the tumor has been debulked.
  24. 24. SURGERY High-concentration adrenaline soaked cottonoids (1:1000) are placed in the nasal cavity for 10 minutes before the surgical procedure begins. The septum is infiltrated with lidocaine with adrenaline 1:100,000. Nasoseptal flap created & preserved First, the intranasal portion of the tumor - debulked to the plane of the skull base to define the attachment to the cribriform plate, and this attachment is cauterized with bipolar electrocautery. Complete sphenoethmoidectomy performed bilaterally Nasal septum transected along the sagittal plane from the crista galli to the sphenoid rostrum approximately 1 cm inferior to the tumor attachment to the septum. This defines the inferior resection margin.
  25. 25. • The tumor-devascularized by cauterizing and transecting the anterior and posterior ethmoidal arteries The bone of the anterior cranial base in the periphery of the tumor – thinned to the resection margins, anteriorly to the posterior table of frontal sinus, posteriorly to the planum sphenoidale, and laterally to the medial orbital walls. The thinned bone-gently fractured and elevated inferiorly off the overlying dura.
  26. 26. • The dura - cauterized and incised longitudinally along the lateral orbital margins, taking care to avoid injury to cortical vessels.  The crista galli – removed , & attached falx cauterized and transected- facilitates rotating the dural specimen posteriorly Dural incision along its posterior margin allows removal of the entire dural specimen en bloc .
  27. 27. When indicated, the olfactory bulbs and nerves are elevated inferiorly off the overlying brain and transected at the level of the posterior dural margin.  Surgical defect extends from the posterior table of the frontal sinus to the planum sphenoidale & to the medial wall of the orbit on either side. Surgical defect closed by nasoseptal flap Small ipsilateral tumors- ipsilateral resection of the anterior cranial base with preservation of olfaction on the contralateral side can be done.
  28. 28. Advantages • improved cosmesis, • reduced brain manipulation, • lower morbidity, • shorter surgical time, • quicker recovery and shorter hospital stay,
  29. 29. Large olfactory groove meningioma • (A) Preoperative (coronal) • B) Axial section close relation of tumor to anterior cerebral arteries at the proximal A2 segment. • (C) Intraoperative- The right lamina papyracea removed to expose the periorbita and provide access to the orbital roof. The anterior and posterior ethmoidal arteries coagulated and sectioned to expose the anterior skull base and provide early devascularization of the tumor. • (D) Intraoperative- Once the tumor has been extensively debulked, gentle extracapsular dissection is performed. • (E) Postoperative-T1-weighted MRI (coronal section) complete resection • of the tumor, cribriform plate, and crista galli. The anterior skull • base reconstructed with the nasoseptal flap. • (F) Postoperative FLAIR sequence MRI (axial section) showing nearly complete resolution of the signal changes and minimal encephalomalacia.
  30. 30. COMPLICATIONS • Worsening of vision. • Intraoperative injury to A2 - it eventually led to a subsequent pseudoaneurysm • Bleeding associated with permanent neurologic deficits. • CSF leak- decreased significantly as a vascularized nasoseptal flap used for reconstruction. • Pulmonary embolus/deep venous thrombosis • Seizures • Pituitary dysfunction • Bacterial meningitis • Myocardial infarction • Loss of olfaction (preserved in cases of unilateral resections )
  31. 31. TRANSPLANUM /TRANSTUBERCULUM APPROACH INDICATIONS Lesions involving the posterior aspect of the anterior skull base and the suprasellar region. Tuberculum sellae meningiomas Giant pituitary adenomas Craniopharyngiomas Epidermoid tumors Rathke cleft cysts
  32. 32. (A) Pituitary macroadenoma with significant suprasellar extension. (B) Craniopharyngioma with large suprasellar cyst above a normal sized sella. (C) Meningioma of the planumsphenoidale(D) Meningioma of the tuberculum sellae.
  33. 33. Endoscopically, these are accessed by transgressing the planum sphenoidale, tuberculum sphenoidale and/or the sella turcica . Hydroscopy is performed by irrigating the field with normal saline under gentle pressure which lifts tissues out of the way, washes away minimal bleeding and distends the cavity to allow for complete inspection
  34. 34. TRANSPLANUM APPROACH • Defined by the removal of the planum sphenoidale and tuberculum sellae to reach skull base. • SURGICAL LIMITS-  Laterally-The optic canals  Anteriorly, the posterior ethmoidal arteries. • The critical anatomic landmark is the medial optic carotid recess. • The most important vital structures related – optic nerve - ICAs - the anterior cerebral arteries (A1, Huebner’s, Anterior communicating and perforators).
  35. 35. ADVANTAGES Provides the most direct route to midline lesions of the suprasellar cistern Do not place critical neurovascular structures between surgeon & lesion Obviates the need of brain retraction Facilitates complete , b/l optic canal decompresssion without manipulation of compressed optic nerve Enables surgeon to remove bone from base of tumor –site for meningioma recurrence Allow surgeon to interrupt blood supply early in operation
  36. 36. CONTRAINDICATIONS • Tumor extending beyond lateral limit of this module • Patient comorbidities that preclude prolonged anaesthesia • Encasement of critical neurovascular structures- not an absolute c/I but surgeon should proceed only if he/she can safely dissect from these structures & has the ability to address surgial emergency (ICA injury)
  37. 37. SURGERY • Nasoseptal flap created & preserved • The posterior third of the bony septum is resected and a piece of vomeric bone is harvested as a rigid buttress for reconstruction of the skull base. • The sphenoid rostrum opened widely • Bilateral posterior ethmoidectomies done • Sphenoid ostia identified & opened widely • Mucosa of the sphenoid sinus removed • identification of the sella, optic nerves, and ICA is verified with frameless stereotactic image guidance
  38. 38. • The tuberculum sellae is thinned with a high-speed diamond drill under constant irrigation till halfway down into the sella • The thinned bone removed & continued along the planum sphenoidale until the underlying dura is exposed. • The anterior limit of resection is the fovea overlying the posterior ethmoid sinuses and cribriform plates. • The superior intercavernous sinus is transected to open the suprasellar area and visualize the pituitary stalk and optic chiasm when necessary.
  39. 39. • The dura cauterized to interrupt the blood supply to the tumor. • Dural and bony attachments of the meningioma resected to prevent recurrence • The tumor capsule sharply dissected away methodically starting with the optic nerve . • ICA identified ( just lateral and inferior to the optic nerve) and tumor traced to the chiasm, along the contralateral optic nerve until the associated ICA is identified and free of tumor Important structures such as the ACA complex,recurrent artery of Heubner, subchiasmal perforating vessels,optic nerves, and pituitary stalk preserved by sharp dissection off the tumor capsule. • Arteries that may appear to be encased can often be dissected free of the tumor • The resection bed is examined using angled endoscopes, with special attention paid to ensuring that the optic nerves and canals are free of tumor
  40. 40. Four corridors -to address lesions of the suprasellar cistern. • The first corridor - passes in front of the optic chiasm - for meningiomas of the planum and tuberculum sellae. • The second corridor - a prechiasmal approach to the third ventricle. ( between the chiasm and the ACA ) - for pathology high in the third ventricle. • The third corridor - below the chiasm and above the pituitary gland. - for cystic lesions arising from the infundibulum that extend into the third ventricle. • The fourth corridor- beneath the pituitary gland (requires superior mobilization of the gland), - for lesions such as craniopharyngiomas,chordomas, and petroclival meningiomas located behind the pituitary gland and infundibulum
  41. 41. • Surgical defect reconstructed with fat to prevent pooling of cerebrospinal fluid (CSF) at the bony defect- a “gasketseal” closure done – nasoseptal flap then rotated to cover the defect, and a tissue sealant (DuraSeal) is used to secure the multilayer graft in place
  42. 42. COMPLICATIONS  INTRAOPERATIVE • Arterial / venous bleeding • Cranial nerve injury • Damage to pituitary gland , stalk & hypothalamus  POSTOPERATIVE • CSF leak • Meningitis • Hematoma formation • Sinusitis • Synechia formation
  43. 43. • Removal of tuberculum meningioma. Preop and post op MRI of a tuberculum meningioma • resected via a transplanum approach. In the endoscopic view, the carotids (C) and optic nerves (ON)
  44. 44. • Hydroscopy. • irrigating the sella with normal saline and using a 45 deg endoscope to obtain 360 deg views around the entire periphery to confirm no residual pockets of tumor. (A) The cavernous carotid (C) and cavernous sinus (CS) are seen. (B) View of the floor of the sella.
  45. 45. CLIVAL LESIONS • The major lesions of the clivus are chordomas and chondrosarcomas • The clivus is most easily approached transphenoidally however the narrowing field of view using a microscope from this anterior approach made pterional and retrosigmoid approaches necessary for tumors with significant lateral extension
  46. 46. TRANSCLIVAL APPROACH • The clivus extends from the dorsum sellae to the foramen magnum. • Transclival approaches - divided into partial (superior, middle, inferior) & complete clivus removal. • A transclival approach provides direct access to the brainstem and vertebrobasilar arterial system.
  47. 47. INDICATIONS • Meningiomas • Chordomas. • Chondrosarcomas • Cholesterol granulomas • Mucocele • Rarely, an aneurysm that cannot be treated by endovascular means or with significant mass effect may be accessed via this approach and clipped
  48. 48. • The upper third - related to the dorsum sellae in the midline and the posterior clinoids in the paramedian region-removed either intradurally via a transsellar approach or extradurally via a subsellar corridor by first performing a superior pituitary transposition • Removal of these structures can provide access to the basilar artery and interpeduncular cistern
  49. 49. • The middle clivus - directly accessed at the posterior aspect of the sphenoid sinus and its resection is limited laterally by both ICAs ascending in the paraclival areas.
  50. 50. • The lower third of the clivus- bone drilling continues inferiorly- limited laterally by the fossa of Rosenmuller and the torus tubarius. • A panclivectomy can extend all the way from the dorsum sellae and posterior clinoids up to the basion at the foramen magnum. • The most related structures for this module - the brain stem, cranial nerves II, III and VI, basilar and vertebral arteries, superior cerebellar arteries, posterior cerebral arteries & respective perforators
  51. 51. ADVANTAGE • Avoid any cerebral retraction • To decrease the incidence of injury to the lower cranial nerves.
  52. 52. CONTRAINDICATIONS • Patient comorbidities that might preclude them from prolonged general anesthesia; • Unfavorable anatomy, such as small sphenoid sinus or diminished space between the internal carotid arteries-makes drilling the clival bone more difficult and risky • Lack of multidisciplinary team cooperation and interaction • Lack of specialized equipment/instruments
  53. 53. DIAGNOSTIC WORKUP The physical examination- neurologic assessment with a special focus on cranial nerve function.  Endoscopic assessment of the nasal cavity- to visualize any nasal lesions and document septal integrity, deviations, and other anatomical findings.  An ophthalmologic examination including a visual field examination
  54. 54. IMAGING • Coronal, axial, and parasagittal CT of the paranasal sinuses and skull base – • evaluate the size of the sphenoid sinus, the position of the internal carotid artery, especially its paraclival portion, and the thickness of the clivus in the sagittal plane. • MRI - to demonstrate the morphology of the soft tissues , for involvement of the carotid artery , vertebrobasilar system & dural sinuses • Magnetic resonance angiography (MRA) or CT angiography(CTA)- to assess relationship between the basilar and internal carotid arteries and the pathology to verify the functional integrity of the circle of Willis and the extent of any carotid artery compromise, and to differentiate an aneurysm from a tumor
  55. 55. SURGERY  Nasoseptal flap created and preserved • B/l ethmoidectomy performed • The sphenoid rostrum and anterior wall of the sphenoid sinus exposed. • The mucosal flap is lifted until both natural sphenoid ostia are in view. • A wide opening of the anterior sphenoid sinus wall created
  56. 56.  The sinus mucosa that lines the clival area reflected , exposing the clival bone.  Care is taken to ensure complete hemostasis at this point in the procedure.  The field should be completely dry before proceeding to the next stage of the procedure  Clival bone fully exposed, and removed by drilling  The limits of the clival bone removal are the floor of the sella superiorly, the foramen magnum inferiorly, and the internal carotid arteries and occipital condyles laterally.
  57. 57. • Exposure at the start of drilling the clival bone. The distance between the internal carotid arteries is an important factor in determining surgical access to this area
  58. 58.  For intradural exposure, the external layer of the dura is first incised with a No. 11 blade.  Bleeding in the basilar plexus not cauterized but packed with hemostatic material  The opening of the internal layer of the dura at the level of the middle and superior clivus must be accomplished with great care to avoid injury to the underlying basilar artery.  Once the dura opened, minor bleeding is stopped by bipolar coagulation, and finally the 0-degree endoscope carefully introduced into the intradural space
  59. 59.  Once the anatomy is appreciated, identify the major vessels of the posterior fossa (basilar artery and branches, anterior inferior cerebellar artery [AICA], vertebral arteries, superior cerebellar and posterior cerebral arteries); the intradural course of cranial nerves III, IV, V, and VI; the brainstem; and the mamillary bodies.  The cerebellopontine angle, cranial nerves VII through XII, and retrosellar regions are best visualized with the 45-degree endoscope
  60. 60.  Meticulous dissection is required to remove the lesion.  At the end of the procedure, the dural defect is sealed with fat and fascia lata, and covered with the flap. The packing is positioned and stays for as long as necessary.
  61. 61. • Endoscopic anatomy following clival resection. (A) Anatomical • specimen demonstrating midline structures. (B) Corresponding intraoperative view. • (C) Anatomical specimen demonstrating left cerebellopontine angle (CPA) using a 45-degree endoscope. (D) Corresponding • intraoperative view of the left CPA
  62. 62. COMPLICATIONAS • Cerebrospinal fluid (CSF) leakage • Nasal bleeding • Bleeding from internal carotid artery, intracranial bleeding, venous bleeding, • Cranial nerve injuries • Infections • Orbital hematoma • Nasal synechia • Nasal infection.
  63. 63. SPINOMEDULLARY JUNCTION LESIONS(TRANSODONTOID APPROACH) • The most common surgical lesion of this region is odontoid pannus usually secondary to rheumatoid arthritis. • An endoscopic endonasal approach to this area was first proposed by Alfieri et al. using cadaveric studies. The first such operation was reported in 2005 • The major advantages of the endonasal route include quicker recovery, faster return to oral alimentation, lower incidence of velopharyngeal insufficiency • major drawback being limitation at the caudal end of the dissection making the procedure not available to all patients
  64. 64. TRANSODONTOID APPROACH Used for resection of the odontoid process in degenerative / inflammatory diseases or to allow for exposure of the ventral medulla and upper cervical spinal cord. • INDICATIONS  Foramen magnum meningiomas  To decompress the brainstem in rheumatoid arthritis patients with degeneration of the upper cervical spine due to compressive pannus • It is defined by the removal of the odontoid process of the axis • The lower third of the clivus is exposed as well as the anterior arch of C1 after dissection of the nasopharyngeal mucosa and the rectus capitis anterior muscle. • The arch of C1 is drilled and the odontoid process is exposed and drilled out. • Pannus removed by sharp and blunt dissection
  65. 65. • The most vital neurovascular structures for this module are the vertebral arteries,  posterior inferior cerebellar arteries (PICAs), brain stem  lower cranial nerves.  The ICAs have to be considered as a risk factor as well because occasionally they can be positioned close to the midline in their parapharyngeal segment under the mucosa
  66. 66. • Preoperative CT scan of a patient with brainstem compression secondary to rheumatoid degeneration (arrow). Decompression is achieved with removal of the odontoid process to the body of C2 and pannus resection
  67. 67. TRANSORBITAL APPROACH • A transorbital approach may be used for access to tumors located within the orbit. The dissection can be extraconal or intraconal
  68. 68. INDICATIONS • Resection of sinonasal lesions that are invading the medial wall of the orbit as sinonasal malignances • To decompress the optic nerves in the presence of unresectable intraconal pathologies • To access intraconal diseases with the goal of resection as for schwannomas, cavernomas and meningiomas
  69. 69. ADVANTAGES • Posterior access to pathology near the orbital apex is excellent via an endoscopic approach. . • Avoid disruption of the orbicularis oculi, lacrimal pump, or canthal ligament disruption
  70. 70. SURGERY • It is defined by the removal of the lamina papyracea or the medial optic canals. • Requires a wide resection of the anterior and posterior ethmoid cells to expose the lateral wall of the sinonasal cavity. • The surgical field is limited laterally by the lamina papyracea and orbital apex deeply • The most important vital structures related to this module are the optic nerves, the anterior and posterior ethmoidal arteries and the ophthalmic artery with its central retina artery branch. • The ocular muscles must be well identified during surgery and dissection can be performed in between them. • Subconjunctival localization and mobilization of eye muscles are extremely helpful during endonasal endoscopic procedures.
  71. 71. ENDOSCOPIC OPTIC NERVE DECOMPRESSION • The most common indication for endoscopic optic nerve decompression is traumatic optic neuropathy
  72. 72. • Surgical intervention is considered if the patient fills any of the criteria listed below:  Fracture of optic canal on CT scan with vision less than 6/60  Fracture of the optic canal with vision . 6/60 but the patient’s vision deteriorates on steroids  Vision is , 6/60 (or there is a deterioration of vision) after 48 hours of steroid treatment with probable canal injury
  73. 73. PROCEDURE • Cotton pledgets containing adrenaline 1:1000 are placed in the nasal cavity over the areas of surgical access for 10 minutes before the surgical procedure. • The lateral nasal wall and septum are infiltrated with 1% aropin with adrenaline 1:100.000. • An uncinectomy, wide antro-stomy combined with anterior and posterior ethmoidectomy is performed.
  74. 74. • The antrostomy is widened superiorly to ensure that the maxillary sinus roof can be easily seen. This defines the orbital floor, allows easier skeletonization of the medial orbital wall, places the infraorbital canal on view, and is an important landmark for defining the level of the skull base posteriorly • Sphenoidotomy performed • The sphenoid should be inspected and the optic nerve, carotid artery and pituitary fossa identified
  75. 75. • Cadaveric dissection image taken of the left sphenoid sinus • demonstrating the fovea ethmoidalis (FE) and lamina papyracea (LP). • ON, optic nerve; CCA, anterior genu of the intracavernous carotid artery; L. OCR, lateral opticocarotid recess; ISS, sphenoid intersinus septum; • SS, sphenoid sinus; MS, maxillary sinus; MT, middle turbinate
  76. 76. • The thick bone overlying the junction of the orbital apex and sphenoid sinus known as the optic tubercle is thinned out with burr • blunt Freer elevator is pushed through the lamina papyracea ,1.5 cm anterior to the junction of the posterior ethmoids air cell(s) and the sphenoid • The bone of the posterior orbital apex flaked off • Once the bone over the orbital apex is removed the bone of the optic canal is approached. Once all the bone has been cleared off the optic canal and the underlying optic nerve sheath is clearly visible, the
  77. 77. • The location of the ophthalmic artery should be kept in mind. The ophthalmic artery usually runs in the posteroinferior quadrant of the nerve • Therefore , the nerve is incised in the upper medial quadrantThis incision is continued onto the orbital periosteum of the posterior orbital apex with resultant protrusion of orbital fat • The orbital fat covering this area of the medial rectus muscle is thin and care should be taken to avoid injuring this muscle • No packs are placed on the nerve or in the sinuses.
  78. 78. COMPLICATIONS • CSF LEAKS • Internal carotid artery injury • The optic nerve sheath (ONS) is incised to release the optic nerve. PO, periorbita; ISS, intersinus septum.
  79. 79. • PETROUS APEX LESIONS • cholesterol granuloma, chordomas, chondrosarcomas and meningiomas • Traditional routes to the petrous apex have included transmastoid approaches that must navigate around the facial nerve and part or all of the otic capsule • middle fossa approaches that involve brain retraction and craniotomy. • The transsphenoidal approach can be faster and safer but only in selected cases. Anatomic variability in pneumatization of the temporal and sphenoid bone along with the location of the lesion and the carotid should be used to guide what is the best approach.
  80. 80. • PTERYGOPALATINE AND INFRATEMPORAL FOSSAL LESIONS • paragangliomas, schwannomas, sphenoid wing meningiomas, and juvenile nasopharyngeal angiofibromas . • A recent review on endoscopic management of juvenile nasopharyngeal angiofibromas concluded that the vast majority of these lesions can be managed safely and effectively via an endoscopic approach . • The major concerns with endoscopic surgery in this region are the difficulty in controlling hemorrhage from the abundant and highly variable vasculature and difficulty in physically accessing the lesion as the dissection proceeds more laterally .
  81. 81. Infratemporal fossa schwannoma. (A) Preop MRI of lesion. (B) Postop MRI of lesion. (C) Endoscopic view of schwannoma. (D) Lateral dissection. (E) Internal debulking. (F) Endoscopic view after resection demonstrating dehiscent dura and carotid..
  82. 82. • RECONSTRUCTION • One of the major concerns in endoscopic skull base surgery is the need for robust reconstruction of the dural defect. • These methods utilized various materials such as dermal grafts, acellular dermis, free mucosal grafts, cartilage, fat, bone and fascia often in multiple layers to close defects at the skull base. • regardless of the material used, there was high success with these techniques for small defects. As defects became larger, the success of reconstruction with these techniques decreased leading to unacceptably high rates of CSF leak in large endoscopic skull base procedures
  83. 83. septal mucosal flap based posteriorly off the posterior septal artery(workhorse of endoscopic skull base reconstruction). transposing the temporoparietal flap through the infratemporal fossa and pterygopalatine fossa and then endoscopically placing the flap for reconstruction Pericranial flaps can also be harvested endoscopically and then transposed into the nasal cavity via a small osteotomy at the nasion.
  84. 84. Haemostasis • operation should start with devascularization of the tumour pedicle. • In some cases, devascularization is visualized by a colour change of the tumour. • Arterial bleeding (sphenopalatine, ethmoidal and internal maxillary arteries) must be prevented, whenever possible, by preventive haemostasis procedures designed to avoid severe bleeding with sudden retraction of proximal fragments (responsible for dramatic retrobulbar haematoma in the case of ethmoidal arteries).
  85. 85. • Unexpected bleeding must be treated either by clips or by bipolar electrocoagulation, and, in the last resort, by packing. • Venous bleeding, particularly due to damage of the cavernous sinus or pterygoid venous plexus, is difficult to control by coagulation and haemostasis can be ensured by packing with Surgicel® (prolonged if necessaryFloseal®, Tissucol®, or Surgicoll. • nasal packing must be adapted to the procedure:
  86. 86. Endonasal packing and dressings • When nasal packs are placed at the end of operation, they are removed on D1 and silastic splints are removed on D10. In children, nasal packs may need to be removed under nitrous oxide or even general anaesthesia. • The nasal cavity is examined at an outpatient visit on D10: the formation of adherent secretions during healing can be responsible for local superinfection,
  87. 87. Limitations of endoscopic skull base surgery • Anatomical limitations • In reality, there are few anatomical limitations to endoscopic endonasal skull base surgery: anatomical studies have shown that most structures encountered during endoscopic endonasal skull base surgery can be either resected or mobilized.
  88. 88. • One of the main anatomical limitations is the ICA. Accidental damage to the ICA can result in bleeding that is often impossible to control. • In some cases, a carotid occlusion test is performed before the operation, but sacrifice of an ICA is associated with a major risk of neurological sequelae. • Zanation et al. described a mobilization technique of the paraclival petrosal part of the ICA: this procedure is reserved to highly skilled operators..
  89. 89. • Cerebral involvement remains a contraindication to endoscopic surgery for most authors . • Optic nerve invasion is also a major limitation, as any resection or mobilization results in permanent visual impairment. • orbital invasion via the inferior orbital fissure or by effraction of periorbital tissues theoretically requires surgical exenteration. • The endonasal technique does not allow satisfactory resection of lesions involving the maxilla, nasal bones. • Finally, by definition, skin extension constitutes a contraindication to endoscopic surgery
  90. 90. • lesion to which access is blocked by the optic • Limitations related to the surgical technique • .Equipment limitations • Surgeon-related limitations The learning curve is an important element in the development of this surgery . Although otorhinolaryngologists are used to working with endonasal endoscopes, this is not always the case for neurosurgeons, who will therefore have to acquire these techniques. • Sinus surgery is generally performed with two hands, and four-hand surgery remains unusual for most surgeons
  91. 91. THANKS

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